ASIO4ALL v2 Instruction Manual.pdf

ASIO4ALL v2

Universal ASIO Driver For WDM Audio

- Instruction Manual -

Last reviewed: 04/02/06

Table of Contents

Introduction........................................................................................................................................................1

Getting Started................................................................................................................................................... 1

Setting up your audio software......................................................................................................................1

Basic Configuration.......................................................................................................................................2

Advanced Configuration.................................................................................................................................... 4

Common Usage Cases Optimizations................................................................................................................6

Using “ReWuschel”........................................................................................................................................... 7

Troubleshooting................................................................................................................................................. 8

Introduction

Welcome to ASIO4ALL v2! This manual enables you to make the most of your ASIO4ALL installation,

especially as it comes to the advanced features newly introduced in this Version of ASIO4ALL.

The ASIO4ALL v2 installer should have added two new icons to your desktop, one being a link to this

documentation and another to launch the ASIO4ALL control panel in off-line mode.

Getting Started

Setting up your audio software

In order to make use of ASIO4ALL, you need to configure your audio software accordingly. How you would

do this depends on your particular application. Generally, you would always enter the audio configuration

menu and select ASIO -> ASIO4ALL v2.

There now should be a button to launch the ASIO control panel. How this button is labeled depends on your

particular software. Once you press this button, the ASIO4ALL control panel should appear. Please consult

the manual of your audio software for further assistance, if necessary!

Sometimes, the audio software indeed would not provide an ASIO control panel option. This is the case

with e.g. Winamp and Foobar 2000, for which ASIO output plugins exist. For configuring ASIO4ALL with

these applications anyway, you can launch the off-line control panel from the desktop. Note that the off-line

control panel launcher works like a mini-ASIO-host of its own and does not reflect the current device status

of any instance of ASIO4ALL that may be open at the same time!

Changes made in the off-line control panel will have an effect only after you restart the audio application.

Settings made in the off-line control panel, however, will have no effect at all for applications that have

been configured with the ASIO4ALL (on-line) control panel launched from inside the audio options dialog

of the application.

Once you made it into the ASIO4ALL control panel, you can now proceed with some basic configuration.

Basic Configuration

Illustration 1: Basic Control Panel View

1. Device List

This is the list of WDM audio devices found in your system. Highlight the device that you want to make

changes to.

Note: All parameter changes always only apply to the currently highlighted device!

If a device name appears in bold , this device is enabled. In the picture above, the CMI8738/C3DX PCI

Audio Device would be enabled while all others are not.

The current state of each device is shown by a small icon and can be either of these:

“Running” - The device has been successfully started by the audio engine.

“Available” - The device should be available for use in this session but has not been started yet.

“Unavailable” - The device is in use by another process or otherwise unavailable to the current session.

“Beyond Logic” - You get this if the device for some unknown reason refuses to start and/or displays

erratic behavior of any kind. Sometimes, closing and re-opening the control panel may cure the situation,

as may unplugging and re-inserting of USB devices. Sometimes, this can also mean the same as

“Unavailable”, whenever the device does not report its current availability or the lack thereof back to

ASIO4ALL.

Note: If the device list is empty, this means that you do not have a single WDM audio device in your

system. Please check with your audio hardware manufacturer for a WDM driver!

2. ASIO Buffer Size

Use the slider to adjust the ASIO buffer size for the device currently highlighted. Smaller buffer size

means lower latency. Once you hear crackles or audio becomes distorted, you need to increase the buffer

size. ASIO buffer size directly relates to audio latency. Thus, you want to get a rather small value here.

Note: If the device list is empty, this means that you do not have a single WDM audio device in your

system. Please check with your audio hardware manufacturer for a WDM driver!

3. Multi-Function Button

Allows you to enable/disable/select the device list item currently highlighted.

Use this to select the currently highlighted device for ASIO operation. In basic mode, you can only select

one device at a time.

If there is no valid action that can be performed with the current item, this button acts as an additional

“Exit”- button.

You can always close the control panel using the “Close” button in the title bar, which has the same

effect.

4. Switch To Advanced Mode

Switches the control panel into “advanced” mode, where you can fix things or completely mess them up

at your disposal. “Advanced” mode is explained in the “Advanced Configuration” section of this

document.

5. Load Default Settings

Pressing this button will reset all configuration options to their initial defaults. Use when audio initially

worked and you later got lost in the configuration process.

6. Status Bar

The most important bit of the status bar is the overload indicator (right where the “6” mark is in the

picture). If the overload indicator flashes, it means just that. You may either want to increase the ASIO

buffer size, or, if it just flashes briefly when there is heavy system load (e.g. When loading a project), you

may just want to ignore it and merely appreciate the coolness of this new feature.

Advanced Configuration

Illustration 2: Advanced Control Panel View

Once the control panel has been switched to advanced mode, things begin to look a little more complicated.

You will have noticed that the items in the device list are now expandable. By expanding the device list, you

can now fully explore the WDM audio architecture of your system.

The device list contains Devices , Device Interfaces and so called “Pins” (this is Microsoft(r) lingo). The

figure above illustrates how they interrelate in the WDM KS hierarchy.

Using the “Action”-button, you can now selectively enable/disable each particular item in the device list.

This way, you can also create multi-device-setups.

Multi-device-setups require that all the devices involved are running from the same clock source. You can

achieve this by daisy-chaining devices via S/PDIF etc. Fortunately, most USB devices will automatically

syncronize themselves for as long as the host controllers they are connected to have a common clock source,

which is trivially true for the USB host controllers embedded in the south bridge on any mainboard.

Note: If devices are not accurately synced, their audio streams are likely to drift apart over time!

On the right side of the panel are the advanced controls (1..5).

1. Latency Compensation

Since ASIO4ALL does not have sufficient knowledge of the underlying hardware/driver architecture, it

can only guess the actual latencies involved.

With these sliders you can compensate for the latencies unknown to ASIO4ALL such that recordings in

your sequencer Software are properly aligned with the rest.

Note: In multi-device-setups the largest respective value of all devices will be used. Therefore, if

different devices have different inherent latencies, audio placement will not be accurate for some devices!

Note: In multi-device-setups the largest respective value of all devices will be used. Therefore, if

different devices have different inherent latencies, audio placement will not be accurate for some devices!

2. Hardware Buffer on/off

Enables the hardware buffer for the highlighted device. This only works for so called “WavePCI”

miniports, as other types of WDM drivers do not usually allow direct access to the hardware buffer.

Adjustment for best hardware buffer performance involves the “ASIO Buffer Size” slider and the “Buffer

Offset” slider (see below). Hardware buffering works best for rather small ASIO buffer sizes. Try

something between 128 and 256 samples as a starter!

The biggest advantage of using the hardware buffer is that this method uses a lot less CPU. In addition, it

may be possible to decrease latencies even further.

In multi-device-setups, it is possible to mix Hardware-buffered devices with devices that are not. This,

however, is not particularly recommended!

If hardware buffering is not supported by a particular audio device, there will be an additional latency of a

couple hundred milliseconds, which is clearly audible.

3. Kernel Buffers/Buffer Offset

If hardware buffering is disabled, this control lets you add up to two more buffers to be queued for audio

output. Each additional buffer increases the output latency of the device by the time it takes to play one

buffer. Therefore, the initial setting of “2” should only be changed on less powerful machines, where

reasonably small ASIO buffer sizes cannot be achieved with the default setting.

If hardware buffering is enabled, this control determines the amount of clearance (in ms) between where

ASIO4ALL will insert data into/read data from the hardware buffer, and the position where ASIO4ALL

currently thinks the hardware read/write position is. Sound complicated already? You haven't even seen

the code that calculates this...

As a general rule: Higher settings increase latencies and stability, lower settings have the adverse effect.

You should, however, be able to achieve a setting that is very close to zero (“4ms” would still be

considered “very close to zero”, while “10ms”, the default, would indicate that there is room for

improvement.)

With Envy24-based PCI-sound cards, there may be an option in your sound card control panel that reads

“DMA Buffer Transfer Latency” (Seen with Terratec products) or similar. You should set this to the

lowest possible value, e.g. “1ms” for best results.

4. Always Resample 44.1<->48 kHz

ASIO4ALL can do real time resampling of 44.1 kHz audio to/from 48 kHz. Resampling will

automatically take place whenever ASIO4ALL is opened for 44.1 kHz and the WDM driver does not

support this sample rate.

There may, however, be instances in which case an AC97 will support 44.1 kHz by resampling internally.

More often than not, however, AC97 resampling quality is extremely poor and/or prone to stability

issues. To work around this, you can enable this option. With at least one incarnation of the SoundMax

WDM driver (smwdm.sys), this option absolutely must be enabled in order to make it work at 44.1 kHz

at all.

5. Force WDM driver to 16 Bit

This option only has an effect if the supported bit depth of the WDM driver is larger than 16, but less

than 24. Some AC97 devices report e.g. 20 Bits resolution but cannot actually be opened for more than

16 Bits resolution. Should this be the case on your system, this option provides a workaround. Originally,

this was introduced as a workaround for an issue with the SigmaTel AC97 WDM driver.

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: